Several molding methods have been developed to make shaped thin plastic shells especially suitable for use in automobile trim components. One such method includes a shell made from dried thermoplastic powder material that is deposited on a heated mold tool. The plastic melts to form a skin contoured with the tool surface. The melted skin is then cured and removed from the tool surface as a finished or nearly finished part.
The molding process is accomplished with a powder box and mold box being sealed at their interface. Much attention has been directed to reducing the waste and subsequent trimming steps associated with this molding process. Waste is formed when the powder resin contacts parts of the mold where such contact is not desired. This waste then must be trimmed in a subsequent step resulting in wasted powder and extra labor steps.
Some efforts to reduce this waste material and the accompanying labor have been attempted. A powder box has been known that includes a skirt portion connected thereto having a lowered edge which contacts the shaped periphery of the mold. The problem with this system is that the skirt must be uniquely adapted to each unique mold shaped periphery. Furthermore, the skirt causes the clearance stroke of the powder box to be significantly lengthened in order to clear the mold thereby increasing cycle time. Furthermore, because the powder box needs to lowered below the mold, deep pits must be dug out under the molding tools to accommodate the lowering of the powder box.
Heat insulators have also been attached to powder boxes in an attempt to cool the neck portion of the powder box where the powder box is connected to the heated mold thereby preventing melting of the powder on the powder box neck. This heat insulator reduces waste build up in the neck area.
What is needed is a heat insulator that can be mounted to the mold and prevent the powder plastic resin from gelling or melting thereon to reduce waste and subsequent trimming and furthermore increases the life of the sealing gasket between the mold tool and powder box.